package/mke2img/mke2img

   1 #!/usr/bin/env bash
   2
   3 # Buildroot wrapper to the collection of ext2/3/4 filesystem tools:
   4 # - genext2fs, to generate ext2 filesystem images
   5 # - tune2fs, to modify an ext2/3/4 filesystem (possibly in an image file)
   6 # - e2fsck, to check and fix an ext2/3/4 filesystem (possibly in an image file)
   7
   8 set -e
   9
  10 main() {
  11     local OPT OPTARG
  12     local nb_blocks nb_inodes nb_res_blocks root_dir image gen rev label uuid
  13     local -a genext2fs_opts
  14     local -a tune2fs_opts
  15     local tune2fs_O_opts
  16
  17     # Default values
  18     gen=2
  19     rev=1
  20     nb_extra_blocks=0
  21     nb_extra_inodes=0
  22
  23     while getopts :hb:B:i:I:r:d:o:G:R:l:u: OPT; do
  24         case "${OPT}" in
  25         h)  help; exit 0;;
  26         b)  nb_blocks=${OPTARG};;
  27         B)  nb_extra_blocks=${OPTARG};;
  28         i)  nb_inodes=${OPTARG};;
  29         I)  nb_extra_inodes=${OPTARG};;
  30         r)  nb_res_blocks=${OPTARG};;
  31         d)  root_dir="${OPTARG}";;
  32         o)  image="${OPTARG}";;
  33         G)  gen=${OPTARG};;
  34         R)  rev=${OPTARG};;
  35         l)  label="${OPTARG}";;
  36         u)  uuid="${OPTARG}";;
  37         :)  error "option '%s' expects a mandatory argument\n" "${OPTARG}";;
  38         \?) error "unknown option '%s'\n" "${OPTARG}";;
  39         esac
  40     done
  41
  42     # Sanity checks
  43     if [ -z "${root_dir}" ]; then
  44         error "you must specify a root directory with '-d'\n"
  45     fi
  46     if [ -z "${image}" ]; then
  47         error "you must specify an output image file with '-o'\n"
  48     fi
  49     case "${gen}:${rev}" in
  50     2:0|2:1|3:1|4:1)
  51         ;;
  52     3:0|4:0)
  53         error "revision 0 is invalid for ext3 and ext4\n"
  54         ;;
  55     *)  error "unknown ext generation '%s' and/or revision '%s'\n" \
  56                "${gen}" "${rev}"
  57         ;;
  58     esac
  59
  60     # calculate needed inodes
  61     if [ -z "${nb_inodes}" ]; then
  62         nb_inodes=$(find "${root_dir}" | wc -l)
  63         nb_inodes=$((nb_inodes+400))
  64     fi
  65     nb_inodes=$((nb_inodes+nb_extra_inodes))
  66
  67     # calculate needed blocks
  68     if [ -z "${nb_blocks}" ]; then
  69         # size ~= superblock, block+inode bitmaps, inodes (8 per block),
  70         # blocks; we scale inodes / blocks with 10% to compensate for
  71         # bitmaps size + slack
  72         nb_blocks=$(du -s -k "${root_dir}" |sed -r -e 's/[[:space:]]+.*$//')
  73         nb_blocks=$((500+(nb_blocks+nb_inodes/8)*11/10))
  74         if [ ${gen} -ge 3 ]; then
  75             # we add 1300 blocks (a bit more than 1 MiB, assuming 1KiB blocks)
  76             # for the journal
  77             # Note: I came to 1300 blocks after trial-and-error checks. YMMV.
  78             nb_blocks=$((nb_blocks+1300))
  79         fi
  80     fi
  81     nb_blocks=$((nb_blocks+nb_extra_blocks))
  82
  83     # Upgrade to rev1 if needed
  84     if [ ${rev} -ge 1 ]; then
  85         tune2fs_O_opts+=",filetype,sparse_super"
  86     fi
  87
  88     # Add a journal for ext3 and above
  89     if [ ${gen} -ge 3 ]; then
  90         tune2fs_opts+=( -j -J size=1 )
  91     fi
  92
  93     # Add ext4 specific features
  94     if [ ${gen} -ge 4 ]; then
  95         tune2fs_O_opts+=",extents,uninit_bg,dir_index"
  96     fi
  97
  98     # Add our -O options (there will be at most one leading comma, remove it)
  99     if [ -n "${tune2fs_O_opts}" ]; then
 100         tune2fs_opts+=( -O "${tune2fs_O_opts#,}" )
 101     fi
 102
 103     # Add the label if specified
 104     if [ -n "${label}" ]; then
 105         tune2fs_opts+=( -L "${label}" )
 106     fi
 107
 108     # Generate the filesystem
 109     genext2fs_opts=( -z -b ${nb_blocks} -N ${nb_inodes} -d "${root_dir}" )
 110     if [ -n "${nb_res_blocks}" ]; then
 111         genext2fs_opts+=( -m ${nb_res_blocks} )
 112     fi
 113     genext2fs "${genext2fs_opts[@]}" "${image}"
 114
 115     # genext2fs does not generate a UUID, but fsck will whine if one
 116     # is missing, so we need to add a UUID.
 117     # Of course, this has to happen _before_ we run fsck.
 118     # Also, some ext4 metadata are based on the UUID, so we must
 119     # set it before we can convert the filesystem to ext4.
 120     # If the user did not specify a UUID, we generate a random one.
 121     # Although a random UUID may seem bad for reproducibility, there
 122     # already are so many things that are not reproducible in a
 123     # filesystem: file dates, file ordering, content of the files...
 124     tune2fs -U "${uuid:-random}" "${image}"
 125
 126     # Upgrade the filesystem
 127     if [ ${#tune2fs_opts[@]} -ne 0 ]; then
 128         tune2fs "${tune2fs_opts[@]}" "${image}"
 129     fi
 130
 131     # After changing filesystem options, running fsck is required
 132     # (see: man tune2fs). Running e2fsck in other cases will ensure
 133     # coherency of the filesystem, although it is not required.
 134     # 'e2fsck -pDf' means:
 135     #  - automatically repair
 136     #  - optimise and check for duplicate entries
 137     #  - force checking
 138     # Sending output to oblivion, as e2fsck can be *very* verbose,
 139     # especially with filesystems generated by genext2fs.
 140     # Exit codes 1 & 2 are OK, it means fs errors were successfully
 141     # corrected, hence our little trick with $ret.
 142     ret=0
 143     e2fsck -pDf "${image}" >/dev/null || ret=$?
 144     case ${ret} in
 145        0|1|2) ;;
 146        *)   errorN ${ret} "failed to run e2fsck on '%s' (ext%d)\n" \
 147                    "${image}" ${gen}
 148     esac
 149     printf "\n"
 150     trace "e2fsck was successfully run on '%s' (ext%d)\n" "${image}" ${gen}
 151     printf "\n"
 152
 153     # Remove count- and time-based checks, they are not welcome
 154     # on embedded devices, where they can cause serious boot-time
 155     # issues by tremendously slowing down the boot.
 156     tune2fs -c 0 -i 0 "${image}"
 157 }
 158
 159 help() {
 160     cat <<_EOF_
 161 NAME
 162     ${my_name} - Create an ext2/3/4 filesystem image
 163
 164 SYNOPSIS
 165     ${my_name} [OPTION]...
 166
 167 DESCRIPTION
 168     Create ext2/3/4 filesystem image from the content of a directory.
 169
 170     -b BLOCKS
 171         Create a filesystem of BLOCKS 1024-byte blocs. The default is to
 172         compute the required number of blocks.
 173
 174     -i INODES
 175         Create a filesystem with INODES inodes. The default is to compute
 176         the required number of inodes.
 177
 178     -r RES_BLOCKS
 179         Create a filesystem with RES_BLOCKS reserved blocks. The default
 180         is to reserve 0 block.
 181
 182     -d ROOT_DIR
 183         Create a filesystem, using the content of ROOT_DIR as the content
 184         of the root of the filesystem. Mandatory.
 185
 186     -o FILE
 187         Create the filesystem in FILE. Madatory.
 188
 189     -G GEN -R REV
 190         Create a filesystem of generation GEN (2, 3 or 4), and revision
 191         REV (0 or 1). The default is to generate an ext2 revision 1
 192         filesystem; revision 0 is invalid for ext3 and ext4.
 193
 194     -l LABEL
 195         Create a filesystem with label LABEL. The default is to not set
 196         a label.
 197
 198     -u UUID
 199         Create filesystem with uuid UUID. The default is to set a random
 200         UUID.
 201
 202   Exit status:
 203     0   if OK
 204     !0  in case of error
 205 _EOF_
 206 }
 207
 208 trace()  { local msg="${1}"; shift; printf "%s: ${msg}" "${my_name}" "${@}"; }
 209 warn()   { trace "${@}" >&2; }
 210 errorN() { local ret="${1}"; shift; warn "${@}"; exit ${ret}; }
 211 error()  { errorN 1 "${@}"; }
 212
 213 my_name="${0##*/}"
 214 main "$@"